Preventive Kiln Maintence

by Highwater Clays Staff

By now most of us have had plenty of time to break our New Year resolutions.  Here's a great resolution to get you back on track and one you can make any time of the year: practicing preventative electric kiln maintenance. By being prepared for routine repairs and performing inspections, you'll keep your firings on track and production running smoothly.

The most important thing is to have spare parts on hand.  You'll invariably need them right before a big show or when a project is due and waiting on shipping is a drag. Here are a few things that should be in every kiln owner's toolbox:

Keep extra elements and feeder wires on hand; at least one extra element for the center of your kiln and an element for the top and bottom.  Depending on what type of kiln you have, element connectors and pins might not be included so have them on hand, as well.  While it is best to change all your elements at once (it saves time in the long run) having a couple extra will get you through crunch times.

It is also wise to have a few more shelves and posts than you normally use.  Shelves will crack someday, or get knocked over, or a glaze will freak out and run all over the place.  Just grab an extra shelf and keep on going.  But do remember to go back and clean glaze runs and touch up with fresh kiln wash. Extra peep plugs are handy, too.  Some types break easily if dropped. Other supplies like kiln cement, hi-temperature wire and kiln wash are good to have for fixing minor cracks and pinning elements back in place. 

For manual kilns equipped with a kiln sitter, keep an extra switch.  They give no warning before going bad and you can't fire without them.  Also have extra kiln sitter parts like a sensing rod, cone rests and adjusting gauge in your toolbox. Along with the switch, these are the most common parts to replace.   Sensing rods wear thin as they age, which can cause the kiln to overfire, which then leads to the cone melting on the supports causing you to replace both.

For digital kilns, have an extra thermocouple ready to replace one that has broken or worn out.  If a thermocouple gets whacked by a shelf, the end connection can crack and it's basically done for.  Another important part that goes out is the relays.  Like switches, they either just stop working or even worse get stuck in the on position.  They can have a life of 5 months to 5 years so have  one ready for emergencies.

Periodically check your kiln for signs of wear.  Look at the cord and plug for singed or charred areas.  Make sure it plugs in securely and isn't loose.  Also check that the metal bands on the kiln are nice and tight.  Vacuum the interior of the kiln every 20-30 firings and gently pin any loose elements back in place.  Pieces of chipped brick can also be pinned back into place.
If you have a kiln sitter, check the calibration using the adjusting gauge.  You want to have the right amount of clearance when the weight drops.  Do this about every 20 firings or so.  Also inspect the sensing rod for thinning and breakage.  For digital kilns, check the thermocouple for flaking.  If it has started to flake, go ahead and clean it up with a toothbrush.  Flaking is a normal occurrence with type K thermocouples and cleaning it up before firing will keep the flakes from sticking to glazed ware.

In addition to having a well stocked tool box and performing routine inspections on your kiln, there are two other very important steps to remember.  I can not emphasis these two enough: keep a kiln log and use cones to monitor your firings, even if it is digital.  When you log your firing times, you'll be able to see when firings are taking longer and you can anticipate element failure.  Cones will help you detect thermocouple drift and kiln sitter problems before they cause big trouble.

Your kiln is a tool that works hard and often completes the final phase of your work.  It deserves a little love every now and then.  So don't hold back, treat your kiln right and it will reward you with many happy firings.

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